MONDAY, July 23 (HealthDay News) -- High blood pressure is a growing problem in teens, partly due to the rising number of obese teens, and federal guidelines suggest specific tests be done to diagnose the effects of the condition.

However, fewer than one in four teens with high blood pressure receives the tests recommended by U.S. National Heart, Lung, and Blood Institute guidelines, a new study finds. On the other hand, about half of those in the study received electrocardiograms (EKGs), which are not recommended to help with diagnosis in children with high blood pressure.

"We found that the most common test used for adolescents was the EKG, a non-recommended test, and that the recommended tests were both infrequently used," said researcher Dr. Esther Yoon, assistant professor of pediatrics at the University of Michigan, Ann Arbor.

"High blood pressure in teens should not be taken lightly," Yoon said. It increases the risk for heart disease and other problems.

The study was published online July 23 in the Archives of Pediatrics & Adolescent Medicine.

Yoon and her colleagues evaluated claims data from 951 Michigan teens, aged 12 to 18, with high blood pressure who were Medicaid patients between 2003 and 2008.

Of these, 24 percent, had an echocardiogram. This test uses sound waves to examine the heart and is recommended to help doctors decide if medication is needed to treat the high blood pressure.

Just 22 percent, about one in five, got a kidney ultrasound to determine if the high blood pressure was affecting the kidneys. This test is also recommended in teens with high blood pressure.

However, half got an EKG, although the guidelines put out by the U.S. National Heart, Lung, and Blood Institute (NHLBI) don't recommend this test in evaluating teens with high blood pressure. An EKG is a noninvasive test that records electrical activity in the heart.

To determine if a child has high blood pressure, a doctor compares his or her blood pressure numbers to average numbers for the child's age, gender and height, according to the NHLBI.

"There is a lot of hesitation," Yoon said. Both doctors and parents, she noted, may explain away a high blood pressure reading in teens, reasoning that they are nervous about seeing the doctor or worried temporarily about something.

The findings call for more research, she added. But they suggest that doctors may not be aware of the guidelines, which Yoon said have been in place since 2004 and updated since then.

"Better education and training of doctors [is needed] to understand how best to use these diagnostic tests for kids with high blood pressure," she said.

Doctors may be using their clinical judgment in deciding which recommended tests to do, said Dr. Sarah de Ferranti, director of the preventive cardiology clinic at Boston Children's Hospital. She co-wrote an editorial accompanying the study.

The study looked only at claims data, she said. For that reason, the study is missing doctors' reasons for not doing certain tests. For instance, the teen may have had mild high blood pressure and the doctor decided to try lifestyle changes first.

Even so, Yoon and de Ferranti said parents can do much to be sure their child, if diagnosed with high blood pressure, gets the best care possible.

If your pediatrician or teen medicine doctor tells you your child has high blood pressure, ask if there is a cause that can be found, de Ferranti said. Obesity increases the risk of high blood pressure. Sometimes, an underlying medical condition, such as a kidney problem, can be causing it.

In many other cases, however, it is what doctors call ''essential hypertension," meaning no cause can be found.

Get instructions about lifestyle changes, de Ferranti said. Your pediatrician may suggest you help your teen start an exercise program, lower salt in the diet or try to lose weight.

If your teen's blood pressure is abnormally high at a doctor's visit, Yoon said, be sure to follow up. Ask the doctor what to do next. This is especially important, she said, if there is a family history of high blood pressure.

The study was funded by the U.S. National Heart, Lung, and Blood Institute.